Catalytic and Structural Properties of Surfactant‐Horseradish Peroxidase Complex in Organic Media

Abstract

A surfactant-horseradish peroxidase (HRP) complex that is catalytically active in organic media has been successfully prepared by a method utilizing water-in-oil (W/O) emulsions. To optimize conditions for preparation of the HRP complex, the effects of some key parameters in the aqueous phase of W/O emulsions were investigated. The surfactant-HRP complex prepared with a nonionic surfactant exhibited a high catalytic activity compared to those with a cationic or anionic surfactant in anhydrous benzene. At the preparation step, the pH of the aqueous solution had a prominent effect on the enzymatic activity of the HRP complex in organic media. Several kinds of salts present in the HRP complex could be employed to enhance the catalytic performance in organic media. However, anionic ions present in the preparation process appeared to lower the catalytic activity owing to the complexation with heme iron. UV-visible absorption spectra of the HRP complex in benzene, which were prepared from a KCN solution (pH 7.0) or an alkaline solution (pH 12), were comparable with those of native HRP in aqueous solution under the same conditions. Resonance Raman spectroscopic studies also revealed that no significant change in the coordination state of the heme iron occurred even after coating the enzyme with surfactant molecules, lyophilization, and solubilization in nonaqueous media.

The influence of structure and composition of a reverse SDS microemulsion on enzymatic activities and electrical conductivities

“…Its activity has been tested in various media-in ionic liquids [4], sol-gel hosts [5,6], biphasic systems [7,8], organic solvents [9], microemulsions, reverse micelles [10][11][12][13][14][15][16], supercritical CO 2 [17], and emulsions [18,19].…”

Horseradish and soybean peroxidases: comparable tools for alternative niches?

“…Additionally, in some anhydrous solvents 280 peroxidase (HRP and SBP) activity was actually increased [75], with additional 281 methods, such as salt activation [76] and excipient aided lyophilisation [77] also 282 resulting in increased peroxidase activity. However, in some low water solvents, 283 peroxidases can lose their confirmational structure [78]; although recent advances in 284 peroxidase encapsulation in amphiphilic matrices [79], the use of reverse micelles 285 [80] and oil emulsions [81] allow for peroxidase activity in an extended range of 286 anhydrous solvents. Reactions carried out in these solvents include hydroxylations, N-287 demethylations and sulphoxidations [2].…”

Solid-in-oil dispersion: A novel core technology for drug delivery systems

“…However, this method is applicable to hydrophilic proteins such as chymotrypsin (Abe et al, 1997a) and peroxidase . The extent of enzymatic catalysis in organic media using surfactant-protein complexes with various types of model protein, such as lipase (Huang et al, 1998), peroxidase (Kamiya et al, 1999(Kamiya et al, , 2000Kamiya and Nagamune, 2002;Okazaki et al, 2000aOkazaki et al, , 2001Michizoe et al, 2003Michizoe et al, , 2004, laccase (Okazaki et al, 2000b;Michizoe et al, 2005) and protease (Okazaki et al, 2000c) was investigated. The overall results are shown in Fig.…”

“…In general, hydrophilic proteins could not be dispersed in organic solvents and precipitated ( Fig. 1c: native horseradish peroxidase (HRP) in anhydrous benzene (Kamiya et al, 2000)), while surfactant-protein complexes prepared using our novel method were easily dispersed in organic solvents ( Fig. 1d: surfactant-HRP complex in anhydrous benzene (Kamiya et al, 2000)), and in most cases, a homogeneous and transparent oil-based dispersion could be prepared.…”

“…Before this procedure was proposed, the yield of proteins was very low (under 30%), except for lipophilic proteins such as lipase. Through this novel process, hydrophilic proteins could be coated with surfactants without loss in yield, and homogeneously dispersed in (Abe et al, 1997a), and representative difference between (c) native HRP and (d) a surfactant-HRP complex in anhydrous benzene (Kamiya et al, 2000). non-aqueous solvents.…”